Fig. 1. Principle of polarization phase-shifting point diffraction interferometry

Fig. 2. Restructuring interference patterns

Fig. 3. Schematics of system errors calibration. (a) Point diffraction measurement mode; (b) system errors measurement mode

Fig. 4. Schematic of experimental step

Fig. 5. Interferograms collected in experiment. (a) Single interferogram; (b) phase-shifting interferograms

Fig. 6. Wavefront aberration detection results of measured objective lens (all measurement results remove Z₁－Z₄ terms of Zernike polynomia, that is, measurement results remove piston, x-tilt, y-tilt, and defocus). (a) Point diffraction measurement results with measurement RMS of 41.67 nm; (b) systematic errors measurement results with 　measurement RMS of 41.07 nm; (c) wave aberration detection results with measurement RMS of 10.49 nm

Fig. 7. Vibration spectrum diagram of platform

Fig. 8. Thirty-two wavefront aberration measurement results under vibration environment. (a) Repeatability of 32 wavefront aberration measurements; (b) measurement repeatability of Z₅－Z₉ after measurement results are fitted with Zernike polynominal